$(document).ready(function(){
	setInterval(function(){
		var windowheight=window.innerHeight;
		var systemmargin=(windowheight-130-50-400)/2;
		var footermargin=windowheight-130-50-400-systemmargin
		if(systemmargin<0){
			systemmargin=0;
		}
		if(footermargin<0){
			footermargin=0;
		}
		$('.body').css('margin-top',systemmargin+'px');
		$('.footer').css('margin-top',footermargin+'px');
		console.log(windowheight);
	},1)
	
})
